public class Example4_9 {
   public static void main(String args[]) {
      SIM simOne = new SIM(13889776509L);
      MobileTelephone mobile = new MobileTelephone();
      mobile.setSIM(simOne);
      System.out.println("手机号码:"+mobile.lookNumber());
      SIM simTwo = new SIM(15967563567L);
      mobile.setSIM(simTwo);  //更换SIM卡
      System.out.println("手机号码:"+mobile.lookNumber());
    }
}
